A Canadian father’s video response to a blunt comment from a man he met in a video store is tugging at the heartstrings of people worldwide.

Rob Scott, of Truro, Nova Scotia, has a 5-year-old son who has Down syndrome. People Magazine reported that Scott was in a video store when he overheard a man tell his son that Down syndrome is “an illness of not knowing anything.”

That comment, Scott said, made him sick.

Too shocked to reply in person, Scott later recorded a video detailing what he wished he would have told the man.

“Down syndrome is literally one of the most beautiful things that’s ever happened in my life,” Scott says amid tears in the video, which has garnered nearly 1 million views on Facebook since being posted Saturday. “[Down syndrome] is fun, it’s brilliant, it’s amazing, it’s funny, it’s kind, it’s loving, it’s cuddly. They’re great teachers, people with Down syndrome. It’s not an illness. It’s not even a disability.”

Scott said he regretted not speaking up to the man because he feels he “failed his son.”

“Down syndrome is the best thing that ever happened to me, but I didn’t say that. I didn’t step up for my son and for other people with Down syndrome. And that was devastating to me in that moment. So I just wanted to right that publicly for myself,” he says in the video.

Along with the more than 870,000 views the video has racked up, Scott’s message has helped rally and lift the spirits of other parents affected by the condition.

“Just found out my little baby girl has downs so thank u so much for this video!” one commenter wrote on Facebook. “It really helps me see her as the kind sweet loving beautiful little girl I know she’s going to be!”

Scott told CBC News the response to his video has overwhelmed him, but that he never intended to criticize the man who inspired it because he never fully understood Down syndrome until he had a child with it.

Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21, which alters development, according to the National Down Syndrome Society. Common physical traits include low muscle tone, small stature and an upward slant to the eyes. It occurs in one in every 691 babies in the US. Individuals with Down syndrome experience cognitive delays, but the effect is mild to moderate.

His son, who was not named, has also taught him other lessons, Scott told CBC News.